Like Alex says, angle is returned in radian with his method. If you want to get angle in degree, write "DEG(ATAN(SY#,SX#))" instead of "ATAN(SY#,SX#)". Angle is 0deg when stick is pointing right. The maximum (minimum) angle is +180deg (-180deg) if you turn stick counterclockwise (clockwise) from 0deg position.